1. Field of the Invention
This invention relates generally to loading and unloading systems, and more particularly to loading and unloading systems for trucks.
2. Description of Related Art
Ramps are commonly used to facilitate loading of objects into, and unloading objects from, truck beds. A problem arises when using a ramp with a typical pickup truck in that that the tailgate gets in the way, requiring a special extension that allows the ramp to extend out over the tailgate. There are various examples of this type of construction, including the following:
Walkden, U.S. Pat. No. 5,795,125, teaches an extendable ramp assembly for a pickup truck. The ramp assembly includes a platform assembly having a hollow interior that is bolted to the floor of the truck bed. A sliding platform is adjustably positioned within the platform assembly to allow for adjusting the angle of incline of an extendable ramp which is attached thereto. The sliding platform is adapted to extend over the tailgate, which remains in a standard position. A hinge plate is connected to the ramp to allow for a relatively smooth and continuous surface between the ramp and the top surface of the platform assembly.
Agee, U.S. Pat. No. 4,601,632, teaches a stowable ramp assembly that is fairly similar to the Walken reference. A generally thin, flat and elongated ramp sleeve is adapted for placement on a truck bed with the rearward end thereof positioned at the rearward end of the bed. An extension sleeve is telescopically slidable within the ramp sleeve and an elongated ramp is telescopically slidably received in the extension sleeve. The extension sleeve is rearwardly slidable to a working position over the lowered horizontal tailgate and the ramp is extendable rearwardly therefrom in the working position and connected to the extension sleeve for up and down pivotal movement of the rearward end of the ramp.
Other similar structures are shown in Noble, U.S. Pat. No. 3,870,170, Uher, U.S. Pat. No. 4,624,619, O'Donnell, et al., U.S. Pat. No. 6,880,194, Goeser, et al., U.S. Pat. No. 4,685,857, Grant, U.S. Pat. No. 5,257,894, Belanger, U.S. Pat. No. 5,570,989, Palmer, Jr., et al., U.S. Pat. No. 6,390,761, Lance, U.S. Pat. No. 5,907,276, Boone, U.S. Pat. No. 5,312,149, Belanger, U.S. Pat. No. 355,518, and Port, U.S. Pat. No. 357,789.
The prior art also teaches various other compartments in a truck undercarriage, including the following:
Foster, et al., U.S. Pat. No. 6,328,366, teaches a vehicle body with an undercarriage storage compartment for storing items such as a spare tire, tools and/or other types of equipment underneath a pick-up truck bed. The vehicle body includes a generally flat truck bed bottom member that extends in a longitudinal direction along the vehicle. The bottom member is mounted to a vehicle structure such as, a vehicle frame, chassis, or unibody member. The storage compartment has a support surface extending underneath the bottom member for supporting items such as the spare tire and associated tools. The storage compartment slides to an open position to allow access to the spare tire and tools and is then returned to a closed position to store the tire and tools within the storage compartment. In one embodiment, the support surface is tiltable to allow ramp access to the truck bed.
A stowable tailgate is also shown in the prior art, including the following:
Bailey, U.S. Pat. No. 6,464,278, teaches a vehicle tail gate mounted on sliding pivots wherein a channel portion of the sliding pivots are on the vehicle and have the initial entry portion sloping downwardly in a direction toward the front end of the vehicle. The tail gate has two spaced apart pins (each preferably with a roller thereon) on each of opposite edges and all four slide in the channels with one pair being on the sloping portion of the track thus by gravity biasing the tail gate into its retracted position in a storage compartment provided under a floor of the vehicle.
Jones, U.S. Pat. No. 4,580,828, and Couvillion, U.S. Pat. No. 5,123,692, teach other embodiments of a tailgate storable beneath a truck bed. P. C. Trautmann, U.S. Pat. No. 3,010,760, teaches a retractable tail gate for a station wagon.
It would thus be beneficial to have a loading and unloading system for a truck with a bed (such as a pickup truck) including a ramp that does not have to be completely removed from a storage area prior to use, and does not require an extension to extend out and over a tailgate.